Staphylococci of Different Virulences Infused Successively into Bovine Udders

Abstract

Infusion of coagulase-negative cocci into normal udders of cows produced a moderate inflammatory reaction and persistent infection. Such quarters were as susceptible as normal controls to the subsequent infusion of coagulase-positive staphylococci. Cows already infected with coagulase-positive staphylococci were probably more susceptible to infusion of such organisms into their noninfected quarters than were normal cows. The lesions found following infusion of coagulase-negative cocci were similar but not as severe as those produced by coagulase-positive organisms. Ductal fibrosis and rosettes occurred with the latter organisms but not with the former coagulase-negative organisms. Atrophy which followed staphylococcal infection was an all or none effect with focal and lobular distribution.